1. Field of the Invention
The invention relates to an apparatus and method for generating pulsating noise in an audio device.
2. Background of the Related Art
Generally, human brain waves are low frequency, around 30 Hz, and can be classified into types based on human mental activity. For example, as shown in FIG. 1, when human mental activity is operating normally, beta waves having a frequency range of about 15˜30 Hz are generated. If a person continuously engages in a mental activity associated with beta waves, he/she is easily exhausted.
Alpha waves having a frequency range of about 8˜14 Hz are generated when a person rests, for example, through meditation and concentrates on something. Theta waves having a frequency range of about 4˜7 Hz are generated when a person displays his/her learning ability or is in light sleep and drowsiness. Delta waves having a frequency range of about 0.5˜3 Hz are generated when a person is in the deepest stage of sleep. Also, gamma waves of more than about 30 Hz are generated when a person is extremely excited or gets angry.
Brain wave induction technology involves artificially synchronizing human brain waves to a desired frequency. Namely, brain wave induction technology employs Frequency Following Effect (FFE) of the human brain, in which, when a person is visually or aurally stimulated at a predetermined frequency, a brain wave corresponding to the predetermined frequency is induced. Accordingly, when a person works under a strain or feels stress due to his/her routine work, he/she can get a refreshment effect as alpha waves having the frequency range of about 8˜14 Hz is induced putting his/her brain in a state similar to when he/she rests and relaxes both mentally and physically.
Optical glasses are used in most brain wave inductors. For example, LEDs with a relatively high light emission are turned on and off ten times per second to induce Alpha wave of about 10 Hz.
Also, technologies inducing brain waves by stimulating auditory senses are classified into, for example, those using a Binaural Beat, those using a Modulated Noise, and those using a Pulsating Noise. Technologies using Binaural Beats are operated such that, when sounds having different frequencies ‘f’ and ‘f+a’ in sinusoidal waves are applied to the right and left ears, respectively, brain waves corresponding to a frequency difference ‘a’ is induced. For example, when sounds at frequencies of 200 Hz and 210 Hz are applied to the right and left eats, respectively, alpha waves of 10 Hz are induced in the brain. However, since sounds having different frequencies in sinusoidal waves should be applied directly to the right and left ears, respectively, users must utilize stereo earphones or a headphone.
Pulsating noise technology operates in such a way that a specific noise or pure sound of a specific frequency is pulsated to provide optical stimulation of a predetermined frequency to users to induce, for example, alpha waves. Therefore, users can use a speaker rather than stereo earphones or a headphone.
Recently, a need to experience brain wave induction phenomenon using pulsating noise has been requested while a user listens to audio through a speaker without wearing earphones or a headphone. However, previously there has been no solution.